1. Field of the Invention
This invention relates to the cutting art, and, more particularly, to an improved annular cutting disc.
2. Description of the Prior Art
In many applications, an annular disc is utilized as a cutting tool. In such applications, the disc is generally a flat, comparatively thin, metallic core which has an outer edge having attachment means for attachment to a rotary motion producing device. An inner annular edge is provided in the core member, and the inner annular edge is the cutting edge.
With the increased activities in the semi-conductor field, wherein crystals of comparatively high unit cost must be precisely cut, such annular cutting discs have been utilized. In order to provide the cutting edge, the prior art annular cutting discs had a coating of a slurry of a nickel matrix with diamond particles therein plated on the cutting edge to provide the actual cutting surface. The diamond particles in the nickel matrix were generally in the range of, for example, 30 to 80 microns.
Materials associated with the semi-conductor industry, such as galium arsenide, silicon, and the like, are comparatively high cost. Consequently, it is desired to minimize the amount of waste material made during the cut of such structures. It is, therefore, desired to make as thin a cut as possible. Additionally, it is necessary that the edges of the material being cut be as planar and free from surface irregularities as possible, because of the precision required in such structures after they are cut.
While the above described configuration has, at times, provided a satisfactory cutting of such materials as galium arsenide, or silicon, or the like, as utilized in the semi-conductor industry, in general, it has been found that when the core is made thinner in order to minimize the loss of the material being cut, precision of the cut was not maintained, due to wobble and/or bowing of the core member during the cutting operation. Additionally, even though the side edges of the coating of the diamond/nickel slurry were ground, it has been found that in areas closely adjacent the core, grinding could not provide the smooth exterior finish required. That is, often there would be one or more diamond particles loosely, or only partially retained by the nickel matrix, and extending therefrom. Such particles could not be ground away, due to the risk of damaging the core during the grinding operation. Therefore, such diamond particles tended to either break loose or to cause an uneven or "ridged" cut in the material being cut, and such cuts or ridges could be in the range of 30 microns deep. Such ridges or cuts tended to degrade the performance of the galium arsenide, silicon, or the like, when it was ultimately utilized in various semi-conductor devices. The bowing or wobbling of the blade not only caused excessive waste during the cut, but also, depending upon the exact motion of the blade, could cause convex or concave edges to the material being cut.
Accordingly, there has long been a need for an annular cutting disc which could provide a comparatively narrow and flat sided cut in semi-conductor materials, such as galium arsenide, silicon, or the like. However, the invention herein is not limited to the application of an annular cutting disc to such materials: rather, it can be advantageously utilized in a plurality of applications.